Unilateral external fixator and its biomechanical effects in treating different types of femoral fracture: A finite element study with experimental validated model.

Previous works had successfully demonstrated the clinical effectiveness of unilateral external fixator in treating various types of fracture, ranging from the simple type, such as oblique and transverse fractures, to complex fractures. However, literature that investigated its biomechanical analyses to further justify its efficacy is limited. Therefore, this paper aimed to analyse the stability of unilateral external fixator for treating different types of fracture, including the simple oblique, AO32C3 comminuted, and 20 mm gap transverse fracture. These fractures were reconstructed at the distal diaphysis of the femoral bone and computationally analysed through the finite element method under the stance phase condition. Findings showed a decrease in the fixation stiffness in large gap fracture (645.2 Nmm-1 for oblique and comminuted, while 23.4 Nmm-1 for the gap fracture), which resulted in higher displacement, IFM and stress distribution at the pin bone interface. These unfavourable conditions could consequently increase the risk of delayed union, pin loosening and infection, as well as implant failure. Nevertheless, the stress observed on the fracture surfaces was relatively low and in controlled amount, indicating that bone unity is still allowable in all models. Briefly, the unilateral fixation may provide desirable results in smaller fracture gap, but its usage in larger gap fracture might be alarming. These findings could serve as a guide and insight for surgeons and researchers, especially on the biomechanical stability of fixation in different fracture types and how will it affect bone unity.

Biomechanical Effects of the Porous Structure of Gyroid and Voronoi Hip Implants: A Finite Element Analysis Using an Experimentally Validated Model.

Total hip arthroplasty (THA) is most likely one of the most successful surgical procedures in medicine. It is estimated that three in four patients live beyond the first post-operative year, so appropriate surgery is needed to alleviate an otherwise long-standing suboptimal functional level. However, research has shown that during a complete THA procedure, a solid hip implant inserted in the femur can damage the main arterial supply of the cortex and damage the medullary space, leading to cortical bone resorption. Therefore, this study aimed to design a porous hip implant with a focus on providing more space for better osteointegration, improving the medullary revascularisation and blood circulation of patients. Based on a review of the literature, a lightweight implant design was developed by applying topology optimisation and changing the materials of the implant. Gyroid and Voronoi lattice structures and a solid hip implant (as a control) were designed. In total, three designs of hip implants were constructed by using SolidWorks and nTopology software version 2.31. Point loads were applied at the x, y and z-axis to imitate the stance phase condition. The forces represented were x = 320 N, y = -170 N, and z = -2850 N. The materials that were used in this study were titanium alloys. All of the designs were then simulated by using Marc Mentat software version 2020 (MSC Software Corporation, Munich, Germany) via a finite element method. Analysis of the study on topology optimisation demonstrated that the Voronoi lattice structure yielded the lowest von Mises stress and displacement values, at 313.96 MPa and 1.50 mm, respectively, with titanium alloys as the materials. The results also indicate that porous hip implants have the potential to be implemented for hip implant replacement, whereby the mechanical integrity is still preserved. This result will not only help orthopaedic surgeons to justify the design choices, but could also provide new insights for future studies in biomechanics.

A Review on Finite Element Modelling and Simulation for Upper Limb of Human Bone and Implant

@#Medical implants are normally used in clinical practice to treat most orthopaedics situations involving bone fractures, deformities, dislocation, and lengthening. It should be noted that specific measures regarding biomechanical and biomaterial characteristics are required for a successful post-surgery procedure. Biomechanical evaluations on the medical implants could be performed by utilising computer and engineering technology. One of them is in silico studies using finite element method that could be simulated in high-performance computer. However, various assumptions are required in computer simulation, such as the constraints on data input and computer resources. This review paper discusses current approaches of constructing a finite element model of human bone with specific material properties for upper limb such as the shoulder joint, humerus, elbow joint, radius and wrist joint. Previous related literatures were reviewed from selected keywords and search engines. To narrow the literature search in this study, inclusion and exclusion criteria of the literature searching were applied. We looked at the current level of knowledge in this field and offered recommendations for future study. In conclusion, studies from previous literature have demonstrated several ways for developing mathematical models and simulating medical implants.

Effects of badminton insole design on stress distribution, displacement and bone rotation of ankle joint during single-leg landing: a finite element analysis.

Previous research has reported that up to 92% of injuries amongst badminton players consist of lower limb, whereby 35% of foot fractures occurred at the metatarsal bone. In sports, insoles are widely used to increase athletes' performance and prevent many injuries. However, there is still a lack of badminton insole analysis and improvements. Therefore, this study aimed to biomechanically analyse three different insole designs. A validated and converged three-dimensional (3D) finite element model of ankle-foot complex was developed, which consisted of the skin, talus, calcaneus, navicular, three cuneiform, cuboid, five metatarsals and five phalanges. Three existing insoles from the market, (1) Yonex Active Pro Truactive, (2) Victor VT-XD 8 and (3) Li-Ning L6200LA, were scanned using a 3D scanner. For the analysis, single-leg landing was simulated. On the superior surface of the skin, 2.57 times of the bodyweight was axially applied, and the inferior surface of the outsole was fixed. The results showed that Insole 3 was the most optimum design to reduce peak stress on the metatarsals (3.807 MPa). In conclusion, the optimum design of Insole 3, based on the finite element analysis, could be a justification of athletes' choices to prevent injury and other complications.

Biomechanical effects of cross-pin's diameter in reconstruction of anterior cruciate ligament - A specific case study via finite element analysis.

For anterior cruciate ligament reconstruction (ACL-R), one of the crucial aspects of treatment is the fixator selection that could provide initial graft fixation post-operatively. Literature on biomechanical stabilities of different sizes of fixators as femoral graft fixation is limited. Therefore, this study aims to analyse the influence of different diameters of cross-pins on the stability of graft fixations after ACL-R via finite element analysis (FEA). In the methodology, three-dimensional (3D) models of three different diameters of cross-pins were developed, of which anterior tibial loads (ATL) were applied onto the tibia. From the findings, the cross-pin with a smaller diameter (4 mm) provided optimum stability than larger diameter cross-pins, whereby it demonstrated acceptable stresses at the fixators (both cross-pin and interference screw) with a different percentage of 28%, while the stresses at the corresponding bones were favourable for osseointegration to occur. Besides, the strains of the knee joint with 4 mm diameter cross-pin were also superior in providing a good biomechanical environment for bone healing, while the recorded strain values at fixators were comparable with a larger diameter of cross-pins without being inferior in terms of deformation. To conclude, the cross-pin with 4 mm diameter depicted the best biomechanical aspects in graft fixation for ACL-R since it allows better assistance for the osseointegration process and can minimise the possibility of the breakage and migration of fixators. This study is not only useful for medical surgeons to justify their choices of pin diameter to treat patients, but also for researchers to conduct future studies.

Stress Distribution and Stability Evaluation of Difference Number of Screws for Treating Tibia Transverse Fracture: Analysis on Patient-Specific Data

@#Introduction: Screws placement may influence the stress distribution and stability of the plate and bone. Implant failures are normally happened in clinical practise when inappropriate number of screws is implemented. Therefore, intensive investigations are needed to provide additional quantitative data on the use of different number of screws. Therefore, this study was conducted to investigate the biomechanical performance of different number of screws configurations on Locking compression plate (LCP) assembly when treating transverse fractures of the tibia bone. Methods: Finite element method was used to simulate tibia bone fracture treated with LCP in standing phase simulation. To accomplish this, a three-dimensional tibia model was reconstructed using CT dataset images. 11 holes of LCP and 36mm of locking screws were developed using SolidWorks software. From this study, there are three models in total have been developed with different number of screws and screw placements. A diaphysis transverse tibia fracture of 4 mm was constructed. Results: In terms of stress distribution, all configurations provide sufficient stress and do not exceeding the yield strength of that material. Conclusion: In conclusion, eight numbers of screws were the optimum configurations in order to provide ideal stability to the bone with displacement of 0.37 mm and 0.91 mm at plate and bone, respectively.

Kinematics and Comfortability Analysis of Orthosis for Patients Associated With Anterior Cruciate Ligament Injury: Hinge Versus Sleeve

@#Introduction: Every month, Sports National Institute (ISN) in Malaysia received around 3 to 4 cases associated with anterior cruciate ligament (ACL) injury involving athletes in hockey, kick volleyball and netball. Knee orthosis is one of treatment method and has been shown to support lower limb joint mechanics, which may protect the ACL injury for becoming worst. In this paper, an investigation was conducted to evaluate the performance of existing knee orthosis for treating ACL injury. Methods: Ten participants which have been grouped into two; six ACL patients (Group 1) and four healthy subjects (Group 2), where they took part in two bracing conditions; 1) with hinge (Brace 1) and 2) sleeve with bilateral hinges (Brace 2). A non-braced condition was included as a baseline measure. Three-dimensional kinematics data were used to calculate knee joint motions. Results: From the findings of ACL subjects, the knee flexion in non-braced condition (49.9°) has high value than others two braces, in which Brace 1 (40.9°) is less value than Brace 2 (44.6°). This shows the Brace 2 have higher degree of freedom than Brace 1. Other than that, the comfortability assessment found that Brace 2 is the most favourable options by participants in terms of less slippage and comfortless condition. Conclusion: In conclusion, the Brace 2 give best performance during dynamic balance activity in individuals who benefit from high degree of freedom and less slippage issue.

Patient-Specific Design of Passive Prosthetic Leg for Transtibial Amputee: Analysis Between Two Different Designs

@#Introduction: Amputee patients are usually utilized prosthetic leg for daily activities such as walking, climbing, and running. However, the current prosthetic leg that available from the market often associated with poor comfortability due to its conventional way of socket manufacturing. Therefore, this research aims to build custom-made passive transtibial prosthetic legs and to evaluate the aspects of biomechanical analysis. Methods: The residual leg of a subject was scanned using the Sense three-dimensional scanner. By referring to scanned residual leg model, two design of prosthetic legs which are the low-cost solid ankle cushion heel (SACH) foot (D1), and the high-cost flex foot (D2), were developed by using computer aided software (CAD), SolidWorks and Meshmixer. Each of the components were then meshed with triangle edge length of 5 mm in 3-Matic software. Marc.Mentat software was used to simulate the midstance phase of a gait cycle where an axial load of 350 N was applied. Results: The overall maximum stress of the D1 (190.2 MPa) was higher than D2 (38.47 MPa). In addition, socket and pylon in D1 showed tendency to yield because the maximum stress is higher than yield stress of respective materials. In displacement analysis, D2 showed higher overall displacement than D1 because the flex foot has higher flexibility. Conclusion: From overall result, prosthetic leg of D2 is better in biomechanical strength as compared with the D1 because it can withstand the loading from subject’s weight without showing any sign of yield.

Stress Distributions and Micromovement of Fragment Bone of Pilon Fracture Treated With External Fixator: A Finite Element Analysis.

Osteoporosis and osteoarthritis are common pathological problems of the human bone tissue. There are some cases of pilon fractures associated with these 2 pathological conditions. In terms of treatment, for a normal and healthy bone with pilon fracture, the use of the Delta external fixator is a favorable option because it can allow early mobilization for patients and provide stability for the healing process. However, the stability of the external fixator differs when there is low bone stiffness, which has not been previously investigated. Therefore, this study was conducted to determine the stability of the external fixator to treat pilon fracture associated with osteoporosis and osteoarthritis, particularly to differentiate the stress distribution and micromovement of fracture fragment. Three-dimensional finite element models of the ankle and foot bones were reconstructed based on the computed tomography datasets. The bones consisted of 5 metatarsal, 3 cuneiform, and 1 each of cuboid, navicular, calcaneus, talus, fibula, and tibia bones. They were assigned with linear isotropic behavior. The ankle joint consisted of ligament and cartilage, and they were assigned with the use of linear links and the Mooney-Rivlin model, respectively. During simulation of the gait cycle, 70 N and 350 N were applied axially to the tibia bone to represent the swing and stance phases, respectively. The metatarsal and calcaneus bones were fixed to prevent any movement of the rigid body. The study found that the greatest von Mises stress value was observed at the pin-bone interface for the osteoporosis (108 MPa) model, followed by the osteoarthritis (87 MPa) and normal (44 MPa) models, during the stance phase. For micromovement, the osteoporosis model had the largest value at 0.26 mm, followed by the osteoarthritis (0.09 mm) and normal (0.03 mm) models. In conclusion, the greatest magnitudes of stress and micromovement were observed for the osteoporosis bone and extra care should be taken to treat pilon fracture associated with this pathological condition.

Thermal Profiling Analysis for Asymmetrically Embedded Tumour with Different Breast Densities

@#Introduction: Detecting breast cancer at earlier stage is crucial to increase the survival rate. Mammography as the golden screening tool has shown to be less effective for younger women due to denser breast tissue. Infrared Thermography has been touted as an adjunct modality to mammography. Further investigation of thermal distribution in breast cancer patient is important prior to its clinical interpretation. Therefore, thermal profiling using 3D computational simulation was carried out to understand the effect of changes in size and location of tumour embedded in breast to the surface temperature distribution at different breast densities. Methods: Extremely dense (ED) and predominantly fatty dense (PF) breast models were developed and simulated using finite element analysis (FEA). Pennes’ bioheat equation was adapted to show the heat transfer mechanism by providing appropriate thermophysical properties in each tissue layer. 20 case studies with various tumour size embedded at two asymmetrical positions in the breast models were analysed. Quantitative and qualitative analyses were performed by recording the temperature values along the arc of breast, calculating of temperature difference at the peaks and comparing multiple thermal images. Results: Bigger size of tumour demands a larger increase in breast surface temperatures. As tumour is located far from the centre of the breast or near to the edge, there was a greater shift of temperature peak. Conclusion: Size and location of tumour in various levels of breast density should be considered as a notable factor to thermal profile on breast when using thermography for early breast cancer detection.

Unifying the seeds auto-generation (SAGE) with knee cartilage segmentation framework: data from the osteoarthritis initiative.

PURPOSE: Manual segmentation is sensitive to operator bias, while semiautomatic random walks segmentation offers an intuitive approach to understand the user knowledge at the expense of large amount of user input. In this paper, we propose a novel random walks seed auto-generation (SAGE) hybrid model that is robust to interobserver error and intensive user intervention. METHODS: Knee image is first oversegmented to produce homogeneous superpixels. Then, a ranking model is developed to rank the superpixels according to their affinities to standard priors, wherein background superpixels would have lower ranking values. Finally, seed labels are generated on the background superpixel using Fuzzy C-Means method. RESULTS: SAGE has achieved better interobserver DSCs of 0.94 ± 0.029 and 0.93 ± 0.035 in healthy and OA knee segmentation, respectively. Good segmentation performance has been reported in femoral (Healthy: 0.94 ± 0.036 and OA: 0.93 ± 0.034), tibial (Healthy: 0.91 ± 0.079 and OA: 0.88 ± 0.095) and patellar (Healthy: 0.88 ± 0.10 and OA: 0.84 ± 0.094) cartilage segmentation. Besides, SAGE has demonstrated greater mean readers' time of 80 ± 19 s and 80 ± 27 s in healthy and OA knee segmentation, respectively. CONCLUSIONS: SAGE enhances the efficiency of segmentation process and attains satisfactory segmentation performance compared to manual and random walks segmentation. Future works should validate SAGE on progressive image data cohort using OA biomarkers.

Augmented reality experimentation on oxygen gas generation from hydrogen peroxide and bleach reaction.

The appreciation and understanding of gas generation through processes is vital in biochemical education. In this work, an augmented reality tool is reported to depict the redox reaction between hydrogen peroxide and sodium hypochlorite solutions, two ubiquitous oxidizing agents, to create oxygen, a combustible gas. As it operates out of smartphones or tablets, students are able to conduct the exercise collaboratively, respond in a manner similar to an actual physical experiment, and able to depict the oxygen volume changes in relation to the volume of hydrogen peroxide of different concentrations used. The tool offers to help students acquire bench skills by limiting handing risks and to mitigate possible student anxiety on handling chemical materials and implements in the laboratory. The feedback received from Year 11 and 12 high school student participants in an outreach exercise indicate the overall effectiveness of this tool. © 2018 by The International Union of Biochemistry and Molecular Biology, 46(3):245-252, 2018.

Interactive knee cartilage extraction using efficient segmentation software: data from the osteoarthritis initiative.

In medical image segmentation, manual segmentation is considered both labor- and time-intensive while automated segmentation often fails to segment anatomically intricate structure accordingly. Interactive segmentation can tackle shortcomings reported by previous segmentation approaches through user intervention. To better reflect user intention, development of suitable editing functions is critical. In this paper, we propose an interactive knee cartilage extraction software that covers three important features: intuitiveness, speed, and convenience. The segmentation is performed using multi-label random walks algorithm. Our segmentation software is simple to use, intuitive to normal and osteoarthritic image segmentation and efficient using only two third of manual segmentation's time. Future works will extend this software to three dimensional segmentation and quantitative analysis.

Medical image visual appearance improvement using bihistogram Bezier curve contrast enhancement: data from the Osteoarthritis Initiative.

Well-defined image can assist user to identify region of interest during segmentation. However, complex medical image is usually characterized by poor tissue contrast and low background luminance. The contrast improvement can lift image visual quality, but the fundamental contrast enhancement methods often overlook the sudden jump problem. In this work, the proposed bihistogram Bezier curve contrast enhancement introduces the concept of "adequate contrast enhancement" to overcome sudden jump problem in knee magnetic resonance image. Since every image produces its own intensity distribution, the adequate contrast enhancement checks on the image's maximum intensity distortion and uses intensity discrepancy reduction to generate Bezier transform curve. The proposed method improves tissue contrast and preserves pertinent knee features without compromising natural image appearance. Besides, statistical results from Fisher's Least Significant Difference test and the Duncan test have consistently indicated that the proposed method outperforms fundamental contrast enhancement methods to exalt image visual quality. As the study is limited to relatively small image database, future works will include a larger dataset with osteoarthritic images to assess the clinical effectiveness of the proposed method to facilitate the image inspection.